Method for tracking defective sectors in re-writable disk media

ABSTRACT

A method for updating a defect list in a DVD can include processing sectors on the DVD during a playback operation; adding references to selected ones of the processed sectors to a defect candidate list; identifying defective sectors among the selected ones of the processed sectors; and, adding references to the identified defective sectors to the defect list. Additionally, the method can include removing from the defect candidate references to each sector for which a corresponding reference has been added to the defect list. The step of adding references to selected ones of the processed sectors to a defect candidate list can include detecting an unrecoverable error during the playback operation; identifying a processed sector associated with the unrecoverable error; and, adding a reference to the identified sector to the defect candidate list. Also, the identifying step can include identifying each sector having a reference in both the defect list and the defect candidate list; removing references to the identified sectors from the defect candidate list; and, determining whether each sector remaining in the defect candidate list is a defective sector.

This application claims the benefit under 35 U.S.C. § 365 ofInternational Application PCT/US00/30605, filed Nov. 7, 2000, which waspublished in accordance with PCT Article 21(2) on May 17, 2001 inEnglish; and which claims benefit of U.S. provisional application Ser.No. 60/164,806 filed Nov. 10, 1999

BACKGROUND OF THE INVENTION

1. Technical Field

The inventive arrangements relate generally to methods and apparatus forproviding advanced operating features for recording data to recordableDVD media, and more particularly to a method and apparatus for trackingdefective sectors in recordable DVD media.

2. Description of the Related Art

Various devices have been developed to enable consumers to record videoand/or audio programs for later presentation. Such devices include taperecorders, video cassette recorders, recordable compact disks, and mostrecently, recordable digital versatile disks (DVD). Hard drives andmagneto optical disks have also been used. A DVD in which data can berecorded once only, and thereafter is essentially a DVD read onlymemory, is referred to by the acronym DVD-R. The acronym DVD-R also hasbeen used generally to refer to write-once, or record-once, technology.

In contrast to DVD-R, several formats exist in which data can berecorded to a DVD, erased and re-recorded. In sum, such a DVD can beoverwritten or rewritten. These DVDs typically are referred to by theacronyms DVD-RAM, DVD-RW and DVD+RW. Although, as of this time nouniform industry standard has been adopted, the acronyms DVD-RAM, DVD-RWand DVD+RW have been used generally to refer to the respectivere-writable DVD technologies. Still, reference herein to re-writable DVDtechnology, devices and methods and recordable DVD media is generallyintended to encompass all of the standards which are now being used, aswell as those which may be developed in the future.

Present DVDs can have a logical file structure in which audio-videocontent can be stored. Specifically, as shown in FIG. 7, at the top ofthe file structure hierarchy of a DVD 700, one or more titles 701 canexist which can loosely correlate to program episode titles. Titles 701can consist of control data 702 in addition to one or more Video ObjectSets 703 (VOBS). The control data 702 can contain information formanaging the title 701. Each VOBS 703 can include a plurality of VideoObjects (VOB) 704. Each VOB 704 preferably includes a plurality of Cells705. Each Cell 705 preferably includes a plurality of Video Object Units(VOBU) 706. Each VOBU 706 roughly correlates to a group of pictureswhich is the smallest addressable chunk in the DVD 700.

Notably, each VOBU 706 can contain an integer number of video frames. Assuch, each VOBU 706 can contain 0.4 to 1.0 seconds of presentationmaterial. A typical VOBU 706 in a commercial motion picture can contain0.5 second of presentation material. Notably, each VOBU 706 can includea sequence of packs 707 positioned in recording order. Preferably, eachVOBU can begin with a navigation pack 708 (NV_PCK or NAV_PACK) which canbe followed by audio-visual data packs 709, for example video packs(V_PCK), audio packs (A_PCK) and sub-picture packs (SP_PCK). The NV-PCK708 can contain navigation information, which can be useful inimplementing trick modes of operation. The NV_PCK 708 also can includepresentation control information (PCI) and data search information(DSI).

Present DVDs can store data using the Universal Disc Format (UDF)specification. As such, present DVDs can include a directory and set offiles within the UDF file format. FIG. 8 illustrates the directorystructure of a typical DVD. According to the DVD-ROM specification, allfiles in a DVD are stored in directories 801, 810, 815 and 820 below theroot directory 800. In particular, DVD-Video data can be stored a singledirectory referred to as the VIDEO_TS directory 801. The VIDEO_TSdirectory 801 can contain a Video Manager and one or more Titles. Asillustrated in FIG. 8, the Video Manager can include a Video Managerinformation file 802, a Video Manager menu file 803, and a Video Managerbackup file 804. Additionally, each Title can include a Video Titleinformation file 805A, 805B, a Video Title menu 806A, 806B, one or morevideo object set files 807A, 807B, 808A, 808B and a Video Title Backupfile 809A, 809B.

Aside from DVD-Video, DVD-Audio information can be stored in ananalogous directory, AUDIO_TS 810. Furthermore, an optional, root-leveldirectory JACKET_P 815 can contain identifying images for the DVD inthree sizes including thumbnails for graphical directories of DVDcollections. Notably, a DVD can include other files stored in one ormore user-defined directories 820. Such directories and files typicallyare placed on the DVD following the DVD-Video data and are ignored byconventional DVD players.

Recordable DVD media can be used for thousands or even tens of thousandsof times for recordings. For each recording, defective sectors in therecordable DVD media potentially can arise. As a result, recordable DVDmedia can accumulate a substantial number of defective sectors duringthe operational lifetime of the recordable DVD media. Yet, defectivesectors in recordable DVD media can inhibit proper playback of datastored in the recordable DVD media. Specifically, defective sectors inthe control data area, such as a control data VOB for a title set, caninvalidate the control data. Moreover, defective sectors in video datain a VOBU can cause video freeze or blockiness. Additionally, defectivesectors in audio data in a VOBU can cause audio distortion or noise.Finally, defective sectors in a menu area can damage a menu.

For analog tape recording technology, such as VCR technology, adefective portion of the video tape may not affect the quality of thesignal substantially during playback. In contrast, for digital discrecording technology, a defective sector can significantly affectplayback quality causing a loss of navigation information and controldata, video freeze, blockiness, loss of audio information and menucorruption. As a result, if defective sectors cannot be identified priorto recording to a re-writable disc, an entire recording can be ruined.Accordingly, defective sector checking can be critical to a successfuldigital disc recording.

Notably, re-writable DVDs each have a defect list that is generated bythe manufacturer. Those sectors which are determined to be defective areadded to the defect list so that the defective sectors will be skippedduring a recording session.

Notwithstanding, in most cases, defect checking cannot be performed inreal-time during a recording session. Moreover, to inspect a re-writableDVD for defective sectors by scanning the entire re-writable DVD canconsume several hours depending upon the capacity of the re-writable DVDand the front-end speed of the re-writable DVD recorder. Accordingly, itcan be impractical to delay the user for the time required to performthe inspection prior to permitting the user to begin recording.

SUMMARY

A method for updating a defect list in a DVD can include playing backthe DVD; detecting at least one unrecoverable error associated with atleast one corresponding sector during the playback; adding a referenceto each sector associated with the unrecoverable error to a defectcandidate list; determining whether each sector referred to in thedefect candidate list is a defective sector; and adding a reference toeach sector determined to be a defective sector to the defect list.Additionally, the method can include removing from the defect candidatelist a reference to each sector for which a corresponding reference hasbeen added to the defect list.

The determining step can include identifying each sector having areference in both the defect list and the defect candidate list;removing the identified sectors from the defect candidate list; and,determining whether each sector remaining in the defect candidate listis a defective sector. The step of identifying each sector having areference in both the defect list and the defect candidate list caninclude sorting the defect candidate list in a structured order; sortingthe defect list in the structured order; and, subtracting the sorteddefect candidate list from the sorted defect list. Notably, thesubtraction can result in the identified sectors. Additionally, thesorting steps can include sorting the defect candidate list in ascendingorder; and, sorting the defect list in ascending order. Similarly, thesorting steps can include sorting the defect candidate list indescending order; and, sorting the defect list in descending order.

A method for updating a defect list in a DVD can include processingsectors on the DVD during a playback operation; adding references toselected ones of the processed sectors to a defect candidate list;identifying defective sectors among the selected ones of the processedsectors; and, adding references to the identified defective sectors tothe defect list. Additionally, the method can include removing from thedefect candidate references to each sector for which a correspondingreference has been added to the defect list.

The step of adding references to selected ones of the processed sectorsto a defect candidate list can include detecting an unrecoverable errorduring the playback operation; identifying a processed sector associatedwith the unrecoverable error; and, adding a reference to the identifiedsector to the defect candidate list. Also, the identifying step caninclude identifying each sector having a reference in both the defectlist and the defect candidate list; removing references to theidentified sectors from the defect candidate list; and, determiningwhether each sector remaining in the defect candidate list is adefective sector.

The step of identifying each sector having a reference in both thedefect list and the defect candidate list can include sorting the defectcandidate list in a structured order; sorting the defect list in thestructured order; and, subtracting the sorted defect candidate list fromthe sorted defect list. Notably, the subtraction can result in theidentified sectors. In one aspect of the method, the sorting steps caninclude sorting the defect candidate list in ascending order; and,sorting the defect list in ascending order. Similarly, in another aspectof the method, the sorting steps can include sorting the defectcandidate list in descending order; and, sorting the defect list indescending order.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a DVD recording device that can be providedwith one or more advance operating features in accordance with theinventive arrangements.

FIG. 2 is a schematic diagram of recordable DVD media.

FIG. 3 is a cut-away view of the recordable DVD media of FIG. 2.

FIG. 4 is a directory tree illustrating a DVD directory and filestructure in accordance with the inventive arrangements.

FIG. 5 is a flow chart illustrating a process for identifying defectivesectors during playback of a DVD.

FIG. 6 is a flow chart illustrating a process for verifying theidentified defective sectors of FIG. 5.

FIG. 7 is a block diagram illustrating a convention DVD physical datastructure.

FIG. 8 is a directory tree illustrating a conventional DVD directory andfile structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Recordable DVD Device

A device 100 for implementing the DVD-ROM backwards-compatible defectmanagement method in accordance with the inventive arrangements taughtherein utilizes a recordable, re-writable disk medium 102 in accordancewith the inventive arrangements is shown in block diagram form inFIG. 1. The re-writable disk medium 102 is embodied as a re-writable DVDin the illustrated embodiment. In many instances, as will be noted, there-writable disk medium can also be, for example, a hard drive or amagneto optical disk (MOD). An example of a MOD is a minidisk. In manyinstances, the inventive arrangements are applicable to video or audioor both video and audio.

The device 100 is capable of writing onto and reading from recordableDVD media, in this example, a re-writable DVD 102. The device comprisesa mechanical assembly 104, a control section 120, a video/audio inputprocessing path 140 and a video/audio output processing path 170. Theallocation of most of the blocks to different sections or paths isself-evident, whereas the allocation of some of the blocks is made forpurposes of convenience and is not critical to understanding theoperation of the device.

The mechanical assembly 104 comprises a motor 106 for spinning the disk102 and a pickup assembly 108 that is adapted to be moved over thespinning disk. The pickup 108 and the motor 106 are controlled by aservo 110. The servo 110 can receive a playback signal of data which canbe read from a spiral track of the disk 102 as a first input. Theplayback signal also can be an input to an error correction circuit 130,which can be considered part of the control section or part of thevideo/audio output processing path.

When reading data from the disk 102, a laser on the pickup assembly 108can direct laser light at an interior layer surface of the disk 102.Depending upon the data stored on the disk 102, the laser light can bemostly reflected or mostly absorbed. The pickup assembly 108 caninterpret reflected light as one type of electrical signal while lightabsorbed by the interior layer surface of the disk 102 can beinterpreted as a second type of electrical signal. In the preferredembodiment, transitions between reflectivity and non-reflectivity aremapped to a digital signal referred to as the playback signal whichcorresponds to the data stored on the disk 102.

By comparison, during recording, a laser on the pickup assembly burnsspots onto a spiral track on the disk 102 in order to digitally recordvideo and/or audio program material. More particularly, the disk 102,which can include at least one interior crystalline recording layer, canexhibit two distinctive states, amorphous or crystalline, each havingdifferent reflectivity characteristics. Those different levels ofreflectivity can be detected by optical sensors in the pickup assembly108.

Prior to recording, the interior recording layer of the disk is in acrystalline state exhibiting high reflectivity. The light intensity of alaser beam can be modulated to write amorphous data marks on the surfaceof tracks in the interior crystalline recording layer. Specifically, theenergy of a laser pulse can quickly raise the surface temperature of theinterior crystalline recording layer above the layer melting point. Onceabove the melting point, the interior layer can transition from acrystalline state of high reflectivity to an amorphous state of lowreflectivity. Subsequently, the rapid cooling of the layer prevents themolecular structure of the interior layer from reorganizing into acrystalline state. Hence, digital data can be mapped to a series oflaser pulses which can write a digital code to the disk 102 which cancorrespond to the digital data.

Notably, depending upon capacity requirements, the disk 102 can haveeither one or two recordable sides. Additionally, the disk 102 can havemultiple recordable layers per side. However, for purposes ofunderstanding the invention, the number of sides and layers isirrelevant. Moreover, in the event of a double-sided recording, it alsois irrelevant whether the recording of both sides of the disk 102 occursfrom one or both sides of the disk 102.

Returning now to FIG. 1, the control section 120 preferably comprises acontroller 122 and a navigation data generation circuit 126. Thecontroller 122 supplies a first input signal to the navigation datageneration circuit 126 and the servo 110 supplies a second input signalto the navigation data generation circuit 126. The servo can also beconsidered part of the control section 120. The navigation datageneration circuit 126 supplies a first input signal to the multiplexer(MUX) 154, which forms part of the video/audio input processing path140. The output of the MUX 154 is an input to an error correction codingcircuit 128. The output of the error correction coding circuit 128 is arecordable input signal supplied to the pickup 108, which will be“burned” onto the spiral track of the disk 102 by the laser.

The controller 122 also preferably has access to the data contained inthe track buffer 172 and record buffer 152 as shown in FIG. 1. Thecontroller 122 can delete, modify, and reformat video data stored in thetrack buffer 172 and record buffer 152 for the purpose of implementingthe inventive arrangements. Control and data interfaces are alsopreferably provided for permitting the controller 122 to control theoperation of packet video encoder 144 and audio encoder 148 forimplementing the inventive embodiments as described herein. Suitablesoftware or firmware is provided in memory for the conventionaloperations performed by controller 122. In addition, program routinesfor the advanced features 134 are provided for controlling thecontroller 122 in accordance with the invention as shall hereinafter bedescribed in greater detail.

A control buffer 132 for viewer activatable functions indicates thosefunctions presently available, namely play, record, reverse, fastforward, pause/play and stop. The pause is a counterpart to pauseoperation in a VCR, for example manually interrupting the play back of aprerecorded program or interrupting the recording of a viewed program toeliminate commercials from the recording. A separate pause buffer 136 isprovided to receive commands for performing the pause during record andplayback function.

The video/audio input processing path 140 is a signal processing circuitfor converting a conventional television signal, for example NTSC orPAL, into digitized packet data, for example MPEG-1 or MPEG-2, fordigital recording by the device 100. The input path 140 comprises anNTSC decoder 142 and video encoder, for example MPEG-1 or MPEG-2, 144for video in, and comprises an audio analog-to-digital converter (A/D)146 and an audio encoder, for example MPEG-1 or MPEG-2, 148. Thedigitized signals are combined in a multiplexer 150 and stored in arecord buffer 152 until an entire packet has been constructed. As eachpacket is constructed, each packet is combined with the output of thenavigation data generation circuit in the MUX 154 and sent to the errorcorrection coding circuit 128. Error correction coding circuit 128 canalso be deemed to be part of the input path 140.

The output processing path 170 comprises a track buffer, or outputbuffer, 172, in which data read from the disk is assembled into packetsfor further processing. The packets are processed by conditional accesscircuit 174 that controls propagation of the packets throughdemultiplexer 176 and into respective paths for video and audioprocessing. The video is decoded by decoder 178, for example from MPEG-1or MPEG-2, and encoded as a conventional television signal by TV encoder180, for example NTSC or PAL. The audio is decoded by circuit 182, forexample MPEG-1 or MPEG-2, and converted to analog form by audiodigital-to-analog (D/A) converter 184. The output processing path 170can be deemed to include the error correction circuit 130, as noted.

Device 100 can represent a machine having, for example, a 1× read and 1×write capability. Such devices can typically have maximum data rates forrecording or playing back of approximately 11 megabits/second. In orderto implement some of the inventive arrangements is necessary to playback (read) and record (write) in a manner that appears to besimultaneous. Apparently simultaneous playing back and recording withsuch a machine would seem to be impossible, but even such a minimalcapability machine can be advantageously operated in accordance with theinventive arrangements to provide apparently simultaneous playing backand recording as well as other inventive arrangements. It will also beappreciated that the inventive arrangements can also be useful fordevices having higher data rates.

DVD Media

For purposes of illustrating the inventive arrangements, programmaterial can be recorded onto recordable DVD media, for example there-writable DVD of FIG. 1, and played back from the re-writable DVD. There-writable DVD 102, as shown in further detail in FIG. 2, can consistof two substrates bonded together by an adhesive layer forming a 1.2 mmthick disk. A center hole 118 can be formed in the center of the disk sothat a gripping device of the motor 106 of FIG. 1 can securely grip thedisk and control the angular motion of the same in accordance with theinventive arrangements.

As in conventional DVD-RAM technology, the re-writable DVD 102 of thepresent invention incorporates a land/groove structure and phase changematerial to record data to disk. The land/groove combination forms acontinuous spiral 112, with data recorded alternately on land andgroove, Data can be written onto the re-writable DVD 102 in an outwardlydirection along the spiral 112, beginning with the smaller radiusportion of the spiral to the larger radius portion of the spiral 112.The several series of three large dots (•••) denote portions of thespiral not shown in the drawing. Each nearly circular, radiallyconcentric section of the spiral 112 can be formed with a side-to-sidewobble, not shown in the drawing, to accommodate media type indexing.Due to difficulties of scale and only portions of the spiral 112 areshown, and these are shown in greatly enlarged scale.

To maintain constant data density across the surface of the re-writableDVD 102, the recording surface is divided into twenty-four (24) annularzones. Each zone has 1,888 tracks, including 944 land tracks and 944grove tracks. Each track is divided into sectors 114 (only a singlesector is shown for simplicity). The innermost zone has seventeen (17)sectors per track. The number of sectors per track increases by one ineach succeeding zone. Hence, the outermost zone contains forty (40)sectors per track. Each sector 114 begins with a read-onlyidentification field, embossed onto the disk surface. Thisidentification field, known as the header, is used to identify thephysical location of the sector and is kept separate from the userrecordable data field, to assure that it is permanently readable. There-writable DVD 102 can further include an embossed area 116 containingread-only data which can identify the type of media, for exampleDVD-RAM, DVD-ROM, or DVD-R.

FIG. 3 is a cut-away view of the re-writable DVD 102 of FIG. 2. As shownin FIG. 3, a re-writable DVD 102 can include both re-writable data areasand embossed data areas. The embossed data for a re-writable DVD 102 canbe located at the innermost portion of the re-writable DVD, referred toas the lead-in area 116. The lead-in area 116 contains information whichcan identify the type of media, such as DVD-RAM or DVD-R. The rewritableDVD 102 similarly can include a lead-out area 124. Notably, each zone120 can have a user area and an associated spare area (not shown). Thespare area can be used for the replacement of any defective sectordetected in the user area. Finally, defective sector addressing can behandled using defect management areas 122. Each defect management area122 can include a list of defective sectors and associated replacementsectors. Additionally, each defect management area 122 can contain thesame information as other defect management areas 122, providing anadditional level of redundancy to improve the reliability of there-writable DVD 102.

It will be appreciated that the advanced features taught herein areapplicable to other kinds of disk media and disk media players andrecorders. Additionally, various modifications of the device illustratedin FIG. 1 and the disk medium illustrated in FIGS. 2 and 3 can be usedtogether to implement the advanced features taught herein in accordancewith the inventive arrangements. In particular, a solution for defectivesector management in accordance with the inventive arrangements caninclude modifications of and additions to hardware, firmware andsoftware in the controller 122 for recording data to recordable DVDmedia.

Checking Defective Sectors for Digital Disc Recorders

Notably, the present invention can be realized in hardware, software, ora combination of hardware and software. Machine readable storageaccording to the present invention can be realized in a centralizedfashion in one computer system, for example the controller 122, or in adistributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus adapted for carrying out the methods described herein isacceptable.

Specifically, although the present invention as described hereincontemplates the controller 122 of FIG. 1, a typical combination ofhardware and software could be a general purpose computer system with acomputer program that, when being loaded and executed, controls thecomputer system and a DVD recording system similar to the controlsection 120 of FIG. 1 such that it carries out the methods describedherein. The present invention can also be embedded in a computer programproduct which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods.

A computer program in the present context can mean any expression, inany language, code or notation, of a set of instructions intended tocause a system having an information processing capability to perform aparticular function either directly or after either or both of thefollowing: (a) conversion to another language, code or notation; and (b)reproduction in a different material form. The invention disclosedherein can be a method embedded in a computer program which can beimplemented by a programmer using commercially available developmenttools for operating systems compatible with the controller 122 describedabove.

In accordance with the inventive arrangements, defective sectors on are-writable disc are detected and a reference thereto placed in a defectlist in the defect management area 122 as shown in FIG. 3. Inconsequence, those defective sectors having a reference stored in thedefect list are not used for recording. More particularly, the defectivesectors on a re-writable disc are checked during each playback of there-writable disc. If an unrecoverable error is detected when playingback a particular sector, the particular sector can be branded as adefective sector candidate. As such, the particular sector can be placedin a defective sector candidate list. If the particular sector later isverified as a genuinely defective sector, a reference to the particularsector can be added to the defect list in the defect management area122.

Notably, additional directories can be added to the DVD directory andfile structure in order to accommodate the defect list and the defectivesector candidate list. Specifically, as shown in the directory treeillustrated in FIG. 4, a DVD directory structure in accordance with theinventive arrangements can include below the root directory 400, aDVD-Video directory 401, a defect list 425, a defect candidate list 430and corresponding defect list and defect candidate list backupdirectories 435, 440. Additionally, as in conventional DVD-Videodirectories, the DVD-Video directory 401 can include a Video Managerinformation file 402, a Video Manager menu file 403, and the VideoManager backup file 404. Additionally, each Title in the DVD-Videodirectory 401 can include a Video Title information file 405A, 405B, aVideo Title menu 406A, 406B, one or more video object set files 407A,407B, 408A, 408B and a Video Title Backup file 409A, 409B. Optionally,the DVD directory structure also can include a DVD-Audio directory 410,the JACKET_P directory 415 and other user-definable directories 420.

A defective sector identification and verification method in accordancewith the inventive arrangements advantageously uses the playbackfunction as a defective sector checking process. In consequence, eachsector suspected of a defect during the playback of the sector can beadded to a defective candidate list. Subsequently, a verificationprocess can determine whether the sectors in the defective candidatelist are to be added to the defect list. FIG. 5 is a flow chartillustrating a process for detecting and tracking suspected defectivesectors during the execution of a DVD playback function. In accordancewith the inventive arrangements, in step 501, first the process canattempt to read a sector in a re-writable DVD. If, in decision step 502,an uncorrectable error is encountered, in step 503 the address of thesector or other suitable reference thereto can be added to a defectcandidate list. If, in decision step 504 it is determined that playbackshould continue, the process can repeat where in step 501, the processcan read the next sector in the DVD.

To reduce redundant verification checks of suspected defective sectorscontained in a defect candidate list, addresses of suspected defectivesectors can be advantageously stored in a structured order in both thedefect list and (for verified defective sectors) the defect candidatelist. Specifically, where both the defect and the defect candidate listare stored in a structured order, each can be compared and sectors whichare not contained in both lists can be more easily identified. Forexample, both the defect list and the defect candidate list can besorted in ascending or descending order. In any event, if in step 504 itis determined that playback should not continue, in step 505, the defectcandidate list can be sorted according to a specified structure, forinstance ascending or descending order. Subsequently, in step 506 theverification process can commence.

FIG. 6 is a flow chart illustrating a process for verifying suspecteddefective sectors subsequent to the detecting and tracking process ofFIG. 5. Significantly, in order to minimally inconvenience the user, theverification process can be advantageously executed just before ejectionof the disc. Specifically, in step 601, an existing defect list can beloaded. Notably, the defect list can be a sorted defect list.Additionally, in step 602 the defect candidate list can be loaded.Significantly, the invention is not limited to retrieving a previouslysorted defect list and defect candidate list. Rather, in an alternativeaspect of the present invention, the lists can be retrieved anddynamically sorted in a structured order, for example ascending ordescending order.

In any event, in step 603, the lists can be compared and those sectorsin the defect candidate list which are already in the defect list arediscarded from the defect candidate list. Notably, where the lists havebeen sorted in a structured order, the defect candidate list need onlybe subtracted from the defect list to determine which sectors in thedefect candidate list have not yet been added to the defect list. Theremaining sectors are determined to be a set of suspected defectivesectors which are to be subsequently verified.

In step 604, the remaining sectors are individually verified todetermine whether, in fact, the sectors are defective. If it isdetermined that a suspected defective sector is in fact defective, instep 605 the defective sector can be added to the defect list andremoved from the defect candidate list. Otherwise, the defective sectoris simply removed from the defect candidate list. Finally, in steps 606and 607, the defect list can be sorted according to the structured orderand written to the defect list in the re-writable DVD.

1. A method for updating a sector defect list in a DVD comprising:executing a viewer operable play function to playback program contentrecorded on the DVD; detecting at least one error associated with atleast one corresponding sector during said playback; adding at least onereference to each sector associated with said error to a defectcandidate list; comparing said defect candidate list and said sectordefect list to identify matching sector references; removing matchingsector references from said defect candidate list to provide an updateddefect candidate list; and updating said sector defect list based uponsaid updated defect candidate list.
 2. The method of claim 1, furthercomprising determining whether each sector remaining in said defectcandidate list is a defective sector prior to updating said sectordefect list based upon on said updated defect candidate list.
 3. Themethod of claim 1, further comprising: removing from said defectcandidate list a reference to each sector for which a correspondingreference has been added to the sector defect list.
 4. The method ofclaim 1, wherein said step of comparing said sector defect list and saiddefect candidate list comprises the steps of: sorting said defectcandidate list in a structured order; sorting the sector defect list insaid structured order; and, subtracting said sorted defect candidatelist from said sorted sector defect list to provide said updated defectcandidate list.
 5. The method of claim 4, wherein said sorting stepscomprise: sorting said defect candidate list in ascending order; and,sorting the sector defect list in ascending order.
 6. The method ofclaim 4, wherein said sorting steps comprise: sorting said defectcandidate list in descending order; and, sorting the sector defect listin descending order.
 7. A method for updating a sector defect list in aDVD comprising: checking sectors on the DVD for errors by playback ofsaid DVD in normal operation; adding references to a defect candidatelist for checked sectors having errors during normal playback;identifying defective sector references in said defect candidate listhaving a corresponding sector reference in the sector defect list; and,removing the identified references from said defect candidate list. 8.The method of claim 7, wherein said step of adding references to adefect candidate list comprises: detecting an unrecoverable error duringsaid playback operation: identifying a processed sector associated withsaid unrecoverable error; and, adding a reference to said identifiedsector to said defect candidate list.
 9. The method of claim 7, whereinsaid identifying step comprises: comparing said defect candidate list tothe sector defect list to identify each sector having a reference inboth the sector defect list and said defect candidate list.
 10. Themethod of claim 8, further comprising: adding sector referencesremaining in said defect candidate list to the sector defect list; andremoving from said defect candidate list references to each sector forwhich a corresponding reference has been added to the sector defectlist.
 11. The method of claim 9, wherein said step of identifying eachsector having a reference in both the sector defect list and said defectcandidate list comprises: sorting said defect candidate list in astructured order; sorting the sector defect list in said structuredorder; and, subtracting said sorted defect candidate list from saidsorted sector defect list, said subtraction resulting in said identifiedsectors.
 12. The method of claim 11, wherein said sorting stepscomprise; sorting said defect candidate list in ascending order; and,sorting the sector defect list in ascending order.
 13. The method ofclaim 11, wherein said sorting steps comprise: sorting said defectcandidate list in descending order; and, sorting the sector defect listin descending order.
 14. A machine readable storage having storedthereon, a computer program having a plurality of code sections forupdating a sector defect list in a DVD, said code sections executable bya machine for causing the machine to perform the steps of: executing aviewer operable play function to playback program content recorded onthe DVD; detecting at least one error associated with at least onecorresponding sector during said playback; adding at least one referenceto each sector associated with said error to a defect candidate list;comparing said defect candidate list and said sector defect list toidentify matching sector references; removing matching sector referencesfrom said defect candidate list to provide an updated defect candidatelist; and updating said sector defect list based upon on said updateddefect candidate list.
 15. The machine readable storage of claim 14,further comprising: determining whether each sector remaining in saiddefect candidate list is a defective sector prior to updating saidsector defect list based upon on said undated defect candidate list. 16.The machine readable storage of claim 14, further comprising: removingfrom said defect candidate list a reference to each sector for which acorresponding reference has been added to the sector defect list. 17.The machine readable storage of claim 14, wherein said step of comparingsaid sector defect list and said defect candidate list comprises thesteps of: sorting said defect candidate list in a structured order;sorting the sector defect list in said structured order; and,subtracting said sorted defect candidate list from said sorted sectordefect list to provide said updated defect candidate list.
 18. Themachine readable storage of claim 17, wherein said sorting stepscomprise: sorting said defect candidate list in ascending order; and,sorting the sector defect list in ascending order.
 19. The machinereadable storage of claim 17, wherein said sorting steps comprise:sorting said defect candidate list in descending order; and, sorting thesector defect list in descending order.
 20. A machine readable storagehaving stored thereon, a computer program having a plurality of codesections for updating a sector defect list in a DVD, said code sectionsexecutable by a machine for causing the machine to perform the steps of:checking sectors on the DVD for errors by playback of said DVD in normaloperation; adding references to a defect candidate list for checkedsectors having errors during normal playback; identifying defectivesector references in said defect candidate list having a correspondingsector reference in the sector defect list; and, removing the identifiedreferences from said defect candidate list.
 21. The machine readablestorage of claim 20, wherein said step of adding references to a defectcandidate list comprises: detecting an unrecoverable error during saidplayback operation; identifying a processed sector associated with saidunrecoverable error; and, adding a reference to said identified sectorto said defect candidate list.
 22. The machine readable storage of claim20, wherein said identifying step comprises: comparing said defectcandidate list to the sector defect list to identify each sector havinga reference in both the sector defect list and said defect candidatelist.
 23. The machine readable storage of claim 20, further comprising;adding sector references remaining in said defect candidate list to thesector defect list; and removing from said defect candidate listreferences to each sector for which a corresponding reference has beenadded to the sector defect list.
 24. The machine readable storage ofclaim 21, wherein said step of identifying each sector having areference in both the sector defect list and said defect candidate listcomprises: sorting said defect candidate list in a structured order;sorting the sector defect list in said structured order; and,subtracting said sorted defect candidate list from said sorted sectordefect list, said subtraction resulting in said identified sectors. 25.The machine readable storage of claim 24, wherein said sorting stepscomprise, sorting said defect candidate list in ascending order; and,sorting the sector defect list in ascending order.
 26. The machinereadable storage of claim 24, wherein said sorting steps comprise:sorting said defect candidate list in descending order; and, sorting thesector defect list in descending order.